Washington State Moves to Divert Cannabis Waste from Landfills with New Legislation

The House in Washington state passed Senate Bill 5376 on February 29, marking a significant step toward establishing regulations for cannabis waste management if the bill is enacted into law.

Presently, cannabis waste, comprising roots, stalks, leaves, and non-“dangerous” stems, finds its way into landfills, contributing to methane gas emissions during decomposition. Methane, accounting for 50% of landfill gas, possesses a heat-trapping potency 28 times greater than carbon dioxide, as highlighted by the U.S. Environmental Protection Agency.

SB-5376 endeavors to curtail cannabis waste generation and mitigate methane emissions in Washington’s landfills. If endorsed by Gov. Jay Inslee, the legislation permits cannabis cultivators and processors to vend plant material containing 0.3% THC or less to the public. This material could then be repurposed for composting or utilized in crafting hemp-based products like hempcrete and hemp fiber products.

Seth Shamberg, operations manager at Blue Roots Cannabis, revealed that their Spokane County-based facility disposes of approximately 2,200 pounds of cannabis waste per month, totaling around 26,400 pounds annually. Shamberg noted the futile recovery attempts once the waste is amalgamated with other organic matter before landfill disposal.

Existing regulations mandate processors to blend cannabis waste with 50% non-cannabis materials like paper waste, cardboard, plastic, or soil, exacerbating methane emission concerns. Heather Trim, executive director of Zero Waste Washington, underscores the bill’s importance in mitigating methane emissions, estimating substantial weekly cannabis waste disposal volumes during the growing season in Washington.

SB-5376, complemented by House Bill 1799 passed in June 2022, aims to diminish methane emissions by diverting organic materials away from municipal landfills. The legislation envisages the collection of organic materials by designated collectors or composting facilities, reducing landfill methane production.

The bill stipulates strict guidelines regarding the reuse of cannabis waste, prohibiting items deemed “dangerous” due to THC content or pesticide residues. All transactions involving cannabis waste must adhere to transparency protocols, with detailed reporting mandated to the Washington State Liquor and Cannabis Board and the Department of Agriculture.

Representative Shelley Kloba hailed the legislation’s potential to foster a circular economy, facilitating revenue streams for cultivators while promoting waste reduction. However, Representative Leonard Christian expressed opposition, citing personal experiences of cannabis’s adverse effects.

In Canada, Health Canada’s recent report unveiled substantial cannabis disposal since legalization in 2018, primarily comprising aged or low-THC products. Industry experts attribute this trend to consumer preference for fresh, high-quality products, highlighting the evolving dynamics of the cannabis market.


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